How can I collect a list of methods with undefined classes in its source?

Example: 

I�ve recently saw that Comanche http server had a package that won�t load in Pharo 3 because is using FileDirectory.

Comanche now loads alright after a patch but..

Instead of iterating lazily this kind of problem in other packages, I would like to make a script that lists all this kind of cases in a given package.

BTW a script like this would help to anticipate potential problems to other developers porting a product to Pharo 

When inspecting one of this methods I�ve sent #recompile to see if it raises an exception but it isn�t. 

How can I perceive, using code, that a compiled method has this kind of problem?

sebastian

o/